It is the right day to remember both the Peterloo Massacre and two (of a number of poems about it): Shelley's 'The Mask of Anarchy' and John Seed's early (1973) Objectivist poem 'August 16th and 17th 1819'. Seed is one of our great Historian-Poets, and I wrote about his poem HERE. He utilises techniques drawn from Charles Reznikoff and applies them to Labour History.
Other Seed posts may be read here and here. I write about him in The Meaning of Form (see here)
and also about the Peterloo poem in Poetry and Praxis After Objectivism. (See here.)